A touchscreen is an electronic visual display that can detect the presence and location of a touch within the display area. The term generally refers to touching the display of the device with a finger or hand. Touchscreens also can sense other passive objects, such as a stylus. Touchscreens are common in devices such as all-in-one computers, tablet computers, and smartphones.
The touchscreen has two main attributes. First, it enables one to interact directly with what is displayed, rather than indirectly with a pointer controlled by a mouse or touchpad. Secondly, it lets one do so without requiring any intermediate device that would need to be held in the hand. Such displays can be attached to computers, or to networks as terminals. They also play a prominent role in the design of digital appliances such as the personal digital assistant (PDA), satellite navigation devices, mobile phones, and video games.
Touch panel sensors disposed on the front side of an image display device and used as an input switch integral with the image display device are easy to use, and thus have been widely used in operation screens of, for example, an automated teller machine of a bank, a ticket-vending machine, a car navigation system, a PDA, a copy machine, and the like. Detection mechanisms of an input point include a resistance film type, a capacitance type, an optical type, an ultrasonic surface elastic wave type, a piezoelectric type, and the like. Among them, the resistance film type detection mechanism is most widely used because of low cost, simple structure, and the like.
The resistance film type touch panel sensor mainly includes an upper electrode, a lower electrode, and a tail. A transparent conductive film provided on a substrate (for example, a film substrate) included in the upper electrode, and a transparent conductive film provided on another substrate (for example, a glass substrate) included in the lower electrode are opposed to each other via a spacer. When a finger, a pen, or the like touches the film side of such a touch panel sensor, both transparent conductive films are brought into contact with each other, so that current flows through the electrodes on both ends of the transparent conductive films. And, a voltage division ratio due to resistances of the respective transparent conductive films is measured thereby to detect the touched position.
While the resistance film type touch panel is capable of detecting stylus, finger, or other devices touching the screen, they suffer from the drawback of accidental activation of the device when the screen accidentally comes into contact with an object, which is common when the device is stored in a purse, a holder, a pocket, and the like. Other types of sensors used with touch screen panels include surface acoustic wave, capacitive, including surface capacitance, projected capacitance, mutual capacitance, self-capacitance, infrared sensors, ultrasonic or acoustic pulse recognition, dispersive signal technology, and optical sensors. Capacitive touch sensor panels have received widespread acceptance in the industry.
Capacitive touch sensor panels can be formed from a matrix of drive and sense lines of a substantially transparent conductive material, such as Indium Tin Oxide (ITO), often arranged in rows and columns in horizontal and vertical directions on a substantially transparent substrate. It is due in part to their substantial transparency that capacitive touch sensor panels can be overlaid on a display to form a touch screen, as described in, for example, U.S. Patent Application Publication No. 2008/0309623, the disclosure of which is incorporated by reference herein in its entirety. Other capacitive touch sensor panels are formed underneath the screen and are comprised of a matrix of drive and sense lines of conductive material present on a substrate.
One such example is an integrated touch screen in which multi-functional elements form a part of the display circuitry of the display system, and can also form part of the touch sensing circuitry of a touch sensing system that senses one or more touches on or near the display. Such an integrated touch screen is disclosed in, for example, U.S. Pat. Nos. 7,859,521, and 7,995,041, the disclosures of each of which are incorporated by reference herein in their entirety.
The present embodiments relate to improved touch sensing arrays that provide resistive or capacitive sensing capabilities. The description herein of advantages or disadvantages of known apparatus, methods, and systems is not intended to limit the scope of the embodiments to their inclusion or exclusion. Indeed, some embodiments may include one or more known apparatus, methods, or systems, without suffering from the disadvantages described herein.